hooking cloth to cloth
A hook modifier uses additional methods to determine what gets hooked.  It only affects vertices that have been assigned to the hook.  One way to do this is to use &quot;hook to new object&quot; operation (or any of its siblings, ctrl h in edit mode for me) which will automatically assign all selected vertices to the hook.  If you want to just do it manually, you can; enter edit mode on the mesh, select the vertices you want hook, and click the &quot;assign&quot; button on the hook modifier.
Vertex groups work in addition to this.  If you tell the hook modifier to use a vertex group, it will only affect verts that are both assigned to the hook and assigned to the vertex group (to the extent that they are weighted to that vertex group.)